Injured or ischemic cardiac tissue has limited intrinsic capacity for regeneration. While stem cell transplantation is a promising approach to stimulating cardiac repair, its success in humans has thus far been limited. Harnessing the therapeutic benefits of stem cells requires a better understanding of their mechanisms of action and methods to optimize their function. Cardiac stem cells (CSC) represent a particularly effective cellular source for cardiac repair, and pre-conditioning CSC with electrical stimulation (EleS) was demonstrated to further enhance their function, although the mechanisms are unknown. Recent studies suggest that transplanted stem cells primarily exert their effects through communicating with endogenous tissues via the release of exosomes containing cardioprotective molecules such as miRNAs, which upon uptake by recipient cells may stimulate survival, proliferation, and angiogenesis. Exosomes are also effective therapeutic agents in isolation and may provide a feasible alternative to stem cell transplantation. We hypothesize that EleS enhances CSC-mediated cardiac repair through its beneficial effects on production of cardioprotective exosomes. Moreover, we hypothesize that the beneficial effects of biventricular pacing in patients with heart failure may in part result from EleS-induced preconditioning of endogenous CSC to promote cardiac repair. With future research, our hypothesis may provide applications to optimize stem cell therapy and augment current pacing protocols, which may significantly advance the treatment of patients with heart disease.

3028 Background: Fluoropyrimidine (FP) based adjuvant chemotherapy (5-Fluorouracil and Capecitabine) increases survival of patients with colorectal and breast cancers. However, 1-5 % of patients experience cardiovascular toxicity, which is not explained by variants in the gene encoding dihydropyrimidine dehydrogenase. Methods: We sought genetic determinants of FP-induced cardiovascular toxicity by performing a genome wide association study of NCI-CTCAE graded cardiovascular toxicity using samples from the QUASAR 2 trial (n=759 patients with colorectal cancer (CRC)). Validation studies (n= 5438 patients with CRC and 1478 patients with breast cancer) were performed in the SCOT, COIN and TACT2 trials. The most commonly reported symptoms were chest pain, angina and arrhythmias with 6 patients experiencing myocardial infarctions. Results: rs4904753, mapping to an intron of D-glutamate cyclase (DGLUCY) was genome wide significant in QUASAR 2 (P =4.38 x 10-16) and validated in SCOT, COIN and TACT2 (P<0.0002 in all studies. rs4904753 was associated with levels of expression of DGLUCY in multiple tissues including the atrial appendage. Under a recessive model, 45.3% (61/137) of patients with cardiac toxicity as compared to 10.2% (691/6786) of controls carried both minor alleles (meta-analysis: OR=7.72, 95% CI 5.31-11.22, P=1.03 x 10-26). Conclusions: The sensitivity, specificity, positive predictive value and negative predictive values of testing for two copies of the toxicity associated allele of rs4904753 were 48%, 90%, 8% and 99% respectively. Clinical implementation of testing for this variant has the potential to identify almost half of those at risk of FP-induced cardiovascular toxicity with high specificity, thereby enabling changes to their clinical management. [Table: see text]

There will be an estimated 228,190 new cases, and 159,480 deaths, from lung cancer in the United States in 2013. Cancer burdens and death are largely due to metastasis in several cancer types, including lung. Much effort has been put into study how cancer cells metastasize. Emerging evidence implicates cancer cells undergo epithelial-mesenchymal transition (EMT) leading to enhanced cell migration and invasion abilities. Exosomes are endosome-derived 30-100 nm biological nanoparticles released from all types of cells but in abundance from tumor cells. Exosomes are released into the extracellular environment and have diverse biological functions. Contents of exosomes consist of proteins and genetic material (mRNA, DNA and miRNA) from the cell of origin. Exosomes are taken up by other cells and induce both genetic and epigenetic changes. Tumor-derived exosomes have been reported to facilitate tumor growth, metastasis and drug resistance. Therefore, understanding the role of tumor-derived exosomes in cellular process would probably enable better management of cancer metastasis. With an aim to prove that exosomes carry the cargo essential for EMT transition leading to cancer metastasis, we treated non-metastatic lung cancer cells with exosomes from metastatic cancers and examined if it would increase growth rate, migratory behavior, and invasiveness of the non-aggressive cancer cells. Our findings suggested: i) exosomes isolated from the lung cancer cell lines, H1299, A549 and H522 had a mean size of 94 - 162 nm; ii) the invasive and metastatic potential of these lung cancer cell lines, as observed by wound healing, migration and invasion assays, was in the following order: H1299 &gt; A549 &gt;&gt; H522; iii) non-invasive H522 lung cancer cells could uptake the PKH-67 labeled exosomes from highly invasive A549 and H1299 cells as reflected by an increased fluorescent signal; iv) the H522 cells treated with A549 or H1299 exosomes exhibited faster wound healing rate, increased migratory behavior, and invasiveness, indicating that exosomes carry the cargo essential for EMT; v) the H522 cells treated with A549 exosomes showed a greater metastatic shift than H1299 treatment; vi) analysis of key EMT-associated proteins in H522 cells treated with exosomes from A549 and H1299 cells indicated changes in expression levels favoring EMT. Expression levels of epithelial markers E-Cadherin, ZO-1, ZEB1, and β-Catenin were downregulated, whereas mesenchymal markers vimentin and Snail were upregulated. Our findings provide insights of a possible role of exosomes in EMT of lung cancer cells. These findings make exosomes a promising platform for future research of EMT (Supported by Duggan Endowment, Helmsley Funds and USPHS grant R25-CA-134283). Citation Format: Radha Munagala, Cameron Campbell, Ramesh Gupta. Role of exosomes in tumor growth and metastasis of lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1054. doi:10.1158/1538-7445.AM2014-1054